Both warm-blooded and cold-blooded desert animals have ways to escape the desert heat. Warm-blooded desert animals, such as rats and mice, rest during the day, often staying in cool underground burrows. At night they search for food. Animals that are out during the day, such as cold-blooded lizards and snakes, are active only for short periods. As their body temperature rises, these reptiles move into the shade in order to cool down. In the early evening, when the sun grows weaker, the reptiles become more active and begin their search for food again.

　　Getting enough water to survive is a major problem for all desert animals. Some desert animals, like desert birds, manage to find water holes. Other desert animals, such as the kangaroo rat and the related jerboa, get water only from the food that they eat. Because these animals eat mainly dry seeds, they must survive on a tiny amount of water.

　　Most deserts have only a small number of frogs and toads because these animals must be near water to survive. Yet even these creatures have adapted（适应）to desert conditions. When small amounts of water collect in temporary streams, the desert-living frogs and toads become active. After a rainfall, they lay their eggs. The eggs grow into tadpoles in a few days and into adults in just four weeks. When the puddles（水坑）dry up, the adult frogs or toads dig into the ground. Their metabolism（新陈代谢）slows, and they stay beneath the ground until the next rain, which may be as good as a year away. Until then, their bodily activities continue at a reduced rate.

　　The camel-often called the ship of the desert--is one of the most successful desert animals. Camels can go for long periods without water, but eventually they must drink. When water becomes available to them after a long drought, they may drink 95 liters of water or more. When water is not available, what helps camels survive the desert heat is the fat stored in their humps（驼峰）. A camel’s hump contains about 12 kilograms of fat. Fat is rich in hydrogen. As the fat is digested, hydrogen from the fat combines with oxygen in the air that the camel breathes. The result is , or water. Each kilogram of fat that a camel digests produces about a liter of water.

(1)Desert animals are usually more active at night because _______.

[　　]

A．it is cooler at night

B．it is easier to find water

C．they like the dark

D．they are less likely to be attacked at night

(2)Which of the following is TRUE according to the passage?

[　　]

A．All the desert animals rest during the day.

B．All the desert animals don’t rest during the day.

C．Cold-blooded desert animals are out most of the day.

D．None of the cold-blooded desert animals go out during the day.

(3)The title for this passage could probably be _______.

[　　]

A．Hot Deserts

B．Desert Animals

C．How Desert Animals Get Water

D．Ways to Escape the Desert Heat

(4)The underlined word “burrows” in the first paragraph can be replaced by _______.

[　　]

In the atmosphere, carbon dioxide acts rather like a one-way mirror or the glass in the roof of a greenhouse which allows the sun's rays to enter but prevents the heat from escaping.

　　 According to a weather expert' s prediction, the atmosphere will be 3℃ warmer in the year 2050 than it is today, if man continues to burn fuels at the present rate. If this warming up took place, the ice caps in the poles would begin to melt, thus raising sea level several metres and severely flooding coastal cities. Also, the increase in atmospheric temperature would lead to great changes in the climate of the northern hemisphere (北半球), possibly resulting in an alteration of the earth's chief food growing zones.

　　  In the past, concern about a man-made warming of the earth has concentrated on the Arctic because the Antarctic is much colder and has a much thicker ice sheet. But the weather experts are now paying more attention to West Antarctic, which may be affected by only a few degrees of warming, in other words, by a warming on the scale that will possibly take place in the next fifty years from the burning of fuels.

　　  Satellite pictures show that large areas of Antarctic ice are already disappearing. The evidence available suggests that a warming has taken place. This fits the theory that carbon dioxide warms the earth.

　　  However, most of the fuel is burnt in the northern hemisphere, where temperatures seem to be falling. Scientists conclude , therefore, that up to now natural influences on the weather have gone beyond those caused by man. The question is: Which natural cause has most effect on the weather?

　　  One possibility is the variable behavior of the sun. Astronomers at one research station have studied the hot spots and "cold" spots (that is, the relatively less hot spots) on the sun. As the sun rotates (使旋转), every 27. 5 days, it presents hotter or "colder" faces to the earth, and different aspects to different parts of the earth. This seems to have a considerable effect on the distribution of the earth's atmospheric pressure, and consequently on wind circulation. The sun is also changeable over a long term: its heat output goes up and down in cycles, the latest trend being downward.

　　  Scientists are now finding shared relations between models of solar weather interactions and the actual climate over many thousands of years, including the last Ice Age. The problem is that the models are predicting that the world should be entering a new Ice Age and it is not. One way of solving this theoretical difficulty is to assume a delay of thousands of years while the solar effects overcome the inertia (惯性) of the earth's climate. If this is right, the warming effect of carbon dioxide might thus be serving as a useful opposed balance to the sun's fading heat .

It can be concluded that a concentration of carbon dioxide in the atmosphere would_________.

   A. mean a warming-up in the Antarctic

   B. raise the temperature of the earth' s surface

C. prevent the sun's rays from reaching the earth's surface

D. explain the cause of  great changes in the climate in the northern hemisphere

The article was written to explain ___________.

A. the greenhouse effect

B. the solar effects on the earth

C. the causes affecting weather

D. the models of solar-weather interactions

Although the fuel consumption is greater in the northern hemisphere, temperatures there　seem to be falling. This is__________.

A. mainly because the levels of carbon dioxide are rising

 B. partly due to changes in the output of solar energy

C. possibly because the ice caps in the poles are melting

D. only due to the effect of the inertia of the earth' s climate

On the basis of their models, scientists believe the opinion that__________.

A. the climate of the world should be becoming cooler

B. the new Ice Age will be delayed by the greenhouse effect

C. the man-made warming effect helps to increase the solar effects

D. it will take thousands of years for the inertia of the earth's climate to take effect

If the assumption about the delay of a new Ice age is correct, ____________.

A. ice would soon cover the northern hemisphere

B. the greenhouse effect could work in favor of the earth

C. the best way to overcome the cooling effect would be to burn more fuels

D. the increased levels of carbon dioxide in the atmosphere could warm up the earth even more quickly

In the atmosphere , carbon dioxide acts rather like a one-way mirror or the glass in the roof of a greenhouse which allows the sun’s rays to enter but prevents the heat from escaping.

   According to a weather expert’s prediction, the atmosphere will be 3 ℃ warmer in the year 2050 than it is today, if man continues to burn fuels at the present rate. If this warming up took place, the ice caps in the poles would begin to melt, thus raising sea level several meters and severely flooding coastal cities. Also, the increase in atmospheric temperature would lead to great changes in the climate of the northern hemisphere(半球), possibly resulting in an alteration of the earth’s chief food growing zones.

   In the past, concern about a man-made warming of the earth has concentrated on the Arctic because the Antarctic is much colder and has a much thicker ice sheet. But the weather experts are now paying more attention to West Antarctic, which may be affected by only a few degrees of warming, in other words, by a warming on the scale that will possibly take place in the next fifty years from the burning of fuels.

   Satellite pictures show that large areas of Antarctic ice are already disappearing. The evidence available suggests that a warming has taken place. This fits the theory that carbon dioxide warms the earth

   However, most of the fuel is burnt in the northern hemisphere, where temperatures seem to be falling. Scientists conclude, therefore, that up to now natural influences on the weather have gone beyond those caused by man. The question is: Which natural cause has most effect on the weather?

   One possibility is the variable behavior of the sun. Astronomers at one research station have studied the hot sports and ‘cold” spots( that is, the relatively less hot spots) on the sun. As the sun rotates(使旋转), every 27.5 days, it presents hotter or colder faces to the earth, and different aspects to different parts of the earth. This seems to have a considerable effect on the distribution of the earth’s atmospheric pressure, and consequently on wind circulation. The sun is also changeable over a long term: its heat output goes up and down in cycles, the latest trend being downward.

   Scientists are now finding shared relations between models of solar weather interactions and the actual climate over many thousands of years, including the last Ice Age. The problem is that the models are predicting that the world should be entering a new Ice Age and it is hot. One way of solving this theoretical difficulty is to assume a delay of thousands of years while the solar effects overcome the inertia(惯性) of the earth’s climate. If this is right, the warming effect of carbon dioxide might thus be serving as a useful opposed balance to the sun’s fading heat.

It can be concluded that concentration of carbon dioxide in the atmosphere would ____.

A. mean a warming-up in the Arctic.              

B. raise the temperature of the earth’s surface.

C. prevent the sun’s rays from reaching the earth’ s surface.

D. explain the cause of great changes in the climate in the northern hemisphere.

The article was written to explain____.

A. the greenhouse effect.          B. the solar effects on the earth.

C. the causes affecting weather.     D. the models of solar weather of solar weather interactions.

Although the fuel consumption is greater in the northern hemisphere, temperature there seems to be falling. This is ____.

A. mainly because the levels of carbon dioxide are rising

B. partly due to changes in the output of solar energy

C. possibly because the ice caps in the poles are melting

D. only due to the effect of the inertia of the earth’s climate

On the basis of their models, scientists are of the opinion that     .

A. the climate of the world should be becoming cooler

B. the new Ice Age will be delayed by the greenhouse effect

C. the man-made warning effect helps to increase the solar effects

D. it will take thousands of years for the interia of the earth’s climate to take effect.

If the assumption about the delay of a new Ice Age is correct, ___.

A. ice would soon cover the northern hemisphere.

B. the greenhouse effect could work in favor of the earth.

C. the best way to overcome the cooling effect would be to burn more fuels.

D. the increased levels of carbon dioxide in the atmosphere could warm up the earth even more quickly.

In the atmosphere, carbon dioxide acts rather like a one-way mirror or the glass in the roof of a greenhouse which allows the sun's rays to enter but prevents the heat from escaping.

　　 According to a weather expert' s prediction, the atmosphere will be 3℃ warmer in the year 2050 than it is today, if man continues to burn fuels at the present rate. If this warming up took place, the ice caps in the poles would begin to melt, thus raising sea level several metres and severely flooding coastal cities. Also, the increase in atmospheric temperature would lead to great changes in the climate of the northern hemisphere (北半球), possibly resulting in an alteration of the earth's chief food growing zones.

　　  In the past, concern about a man-made warming of the earth has concentrated on the Arctic because the Antarctic is much colder and has a much thicker ice sheet. But the weather experts are now paying more attention to West Antarctic, which may be affected by only a few degrees of warming, in other words, by a warming on the scale that will possibly take place in the next fifty years from the burning of fuels.

　　  Satellite pictures show that large areas of Antarctic ice are already disappearing. The evidence available suggests that a warming has taken place. This fits the theory that carbon dioxide warms the earth.

　　  However, most of the fuel is burnt in the northern hemisphere, where temperatures seem to be falling. Scientists conclude , therefore, that up to now natural influences on the weather have gone beyond those caused by man. The question is: Which natural cause has most effect on the weather?

　　  One possibility is the variable behavior of the sun. Astronomers at one research station have studied the hot spots and "cold" spots (that is, the relatively less hot spots) on the sun. As the sun rotates (使旋转), every 27. 5 days, it presents hotter or "colder" faces to the earth, and different aspects to different parts of the earth. This seems to have a considerable effect on the distribution of the earth's atmospheric pressure, and consequently on wind circulation. The sun is also changeable over a long term: its heat output goes up and down in cycles, the latest trend being downward.

　　  Scientists are now finding shared relations between models of solar weather interactions and the actual climate over many thousands of years, including the last Ice Age. The problem is that the models are predicting that the world should be entering a new Ice Age and it is not. One way of solving this theoretical difficulty is to assume a delay of thousands of years while the solar effects overcome the inertia (惯性) of the earth's climate. If this is right, the warming effect of carbon dioxide might thus be serving as a useful opposed balance to the sun's fading heat .

66. It can be concluded that a concentration of carbon dioxide in the atmosphere would_________.

   A. mean a warming-up in the Antarctic

   B. raise the temperature of the earth' s surface

C. prevent the sun's rays from reaching the earth's surface

D. explain the cause of  great changes in the climate in the northern hemisphere

67.The article was written to explain ___________. 

A. the greenhouse effect

B. the solar effects on the earth

C. the causes affecting weather

D. the models of solar-weather interactions

68. Although the fuel consumption is greater in the northern hemisphere, temperatures there　seem to be falling. This is__________.

 A. mainly because the levels of carbon dioxide are rising

 B. partly due to changes in the output of solar energy

C. possibly because the ice caps in the poles are melting

D. only due to the effect of the inertia of the earth' s climate

69. On the basis of their models, scientists believe the opinion that__________.

A. the climate of the world should be becoming cooler

B. the new Ice Age will be delayed by the greenhouse effect

C. the man-made warming effect helps to increase the solar effects

D. it will take thousands of years for the inertia of the earth's climate to take effect

70. If the assumption about the delay of a new Ice age is correct, ____________.

A. ice would soon cover the northern hemisphere

B. the greenhouse effect could work in favor of the earth

C. the best way to overcome the cooling effect would be to burn more fuels

D. the increased levels of carbon dioxide in the atmosphere could warm up the earth even more quickly